Controller for electric motors.



A. W. SGHRAMM & E. B. WILPORD.

CONTROLLER FOR ELEOTRIG MOTORS.

APPLICATION FILED JULY 10, 1911.

Patented Sept. 5, 1911.

3 SHEETSSHEET 1.

A. W. SOHRAMM & E. B. WILPORD.

CONTROLLER FOR ELECTRIC MOTORS.

APPLICATION FILED JULY 10, 1911.

1,002,766, Patented Sept. 5, 1911.

-3 SHEETS-SHEET 2.

A. W. SOHRAMM & E. B. WILPORD.

CONTROLLER FOR ELECTRIC MOTORS.

I APPLICATION FILED JULY 10,1911, 1,002,766. Patented Sept. 5,1911.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

ADOLPH W. SCHRAMM, OF RIVERTON, NEW JERSEY, AND EDWARD B. WILFORD, OF

MERION, PENNSYLVANIA, ASSIGNORS TO ELECTRO DENTAL MANUFACTURING COM- PANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

CONTROLLER FOR ELECTRIC MOTORS.

Specification of Letters Patent.

Application filed July 10, 1911.

Patented Sept. 5, 1911.

Serial No. 637,649.

To all whom it may concern:

Be it known that we, ADoLPH W. SCHRAMM, and EDWARD B. VVILFoRo, citizens of the United States, and residents of Riverton, Burlington county, New Jersey, and Merion, Montgomery county, Pennsylvania, respectively, have invented certain Improvements in Controllers for Electric Motors, of which the following is a specification.

One feature of this invention consists in the provision of novel means for controlling the position and operation of the actuating lever forming part of a foot controller such as is customarily used by dentists for governing the operation of the electric motors employed in certain dental operations.

One object of the invention is to provide a device which may be adjusted to-cause the.

actuating lever either to remain in a given position until it is tripped by the operator, or to be at all times free to return to its normal or off position whenever it is not positively held by the operator.

Another object of the invention is to provide a device of the character indicated, for use in connection with the actuating lever of a foot controller, with means whereby it may be conveniently adjusted to operate in either of the two ways above described; the invention also contemplating a novel, form of indicator for showlng its adjustment at any particular time. I

It is also desired to provide a device having the above noted characteristics which shall be relatively simple and compact in construction, as well as of such a nature that it' shall not be likely to get out of order or require repairs.

These objects and other advantageous ends are secured as hereinafter set forth, reference being had to the accompanying drawings, in which Figure 1, is a perspective view illustrating a well known form of foot controller to which the invention may be applied; Fig. 2, is a perspective view of the interior mechanism of the controller; Fig. 3, is a transverse vertical section taken through the central spindle of the apparatus shown in Fig. 2; Fig. 4, is a plan on a reduced scale of the mechanism shown in Fig. 2; Figs. 5 and 6 are horizontal sections taken on the line a-a, and 12-1), Fig. 3; Figs. 7 and 8 are respectively a fragmentary plan and a vertical section illustrating one modified form of the invention; Figs. 9 and 10, are'two plans, partly in section, illustrating a further modification of the invention, the figures showing the parts in two different positions, and Fig. 11, is a side elevation partly in section, further showing the detail construction of the device illustrated in Figs. 9 and 1 0. In the above drawings 1 represents a substantially cylindrical casing having a base 2 and a removable cover 3 which includes a vertical curved portion 4 whose lower edge is spaced away from the similarly shaped upwardly projecting part 4 of the casing to form a slot 5.

It is noted that the surfaces of the parts 4 and 1 are depressed inwardly some distance from the outside surface of thecasing, with which they are concentric, and in the space so formed is a foot or operating lever 6 projecting through the slot .5 from the interior of the casing. WVithin the casing is 'rcmovably mounted the metallic framework is a pair of similar metallic contact strips 13 and 14, rigidly connected together, and having a sheet of insulating material between them. These strips are not only insulated from each other but are also insulated from the frame 7 and are designed to be engaged by a pair of contact arms 15 and 16 also insulated from the sleeve 9 to which they are rigidly connected. Connected to the sleeve 9 by a set screw 17 is an arm 18 'havingpivoted to it the operating lever 6 and practically forming therewith a broken lever. For convenience in manufacture the operating lever 6 has rigidly fastened to its inner end a casting 19 having two branches 20 and 21 constituting pawls hereafter referred to. This casting, and therefore said lever 6, is pivotally connected to the arm 18 by means of a screw or bolt 22.

The part 19 of the operating lever has a downwardly extending lug 23 normally lying between two arms 24 and 25 respectively forming part of or connected to two sleeves 11 and 11, the latter of which is mounted on the spindle 8 while the other is carried by said sleeve 11. A piece 7 attached to the main frame 7 has a downwardly projecting lug 26 immediately in front of the lug 23 and so placed as to serve as a stop for the arms 24 and 25. Both of these latter are normally maintained in engagement with the stop 26 by a spring 12, one end of which is connected to the sleeve 11 while the other is connected to the sleeve 11;this latter extending through said spring to the lower end thereof where it has a collar 28 held to it by a set screw and directly connected with the second end of the spring.

, The two sleeves 11 and 11 have rearwardly extending double contact members 29, 30, Fig. 6, placed to cooperate with various fixed contacts 32, 33, and 34 carried on a block of insulating material 35 mounted on the main frame of the controller. The detail arrangement of these parts of the device, having to do with its functions as an electric controller, constitute no part of the present invention and we have therefore not described nor illustrated them in detail, inasmuch as said invention has to do rather with the means whereby the action and position of the operating lever 6 may be governed. In order,

to retain this lever in any given position with its attached contacts in engagement with certain ones of the fix'ed contacts, we provide a strip 50 of a generally semiannular form, having near its ends on its inner edge, two series of notches or teeth 36 and 37 so placed as to be engaged by the holding arms or pawls 20 and 21 respectively' when the operating lever 6 is displaced sufficiently from its normal position. This strip has rigidlyfastened to, it two guide rods 38 and '39 projecting downwardly at right angles to its plane and slidably mounted in lugs 40 and 41 projecting from and forming part of the main frame. The arrangement of the toothed strip and these bars is such that when the former is in its lower position, its teeth are in the same plane as that of the pawl or holding arms 20 and 21, while when it is elevated it is so far above this plane that its teeth cannot be engaged by said pawls, which then glide along the inner surface of the piece 7*. For releasably holding said strip in either of its two extreme positions we provide a spring 43 consisting of a piece of flat resilient material having a bowed. central part, and two parallel ends provided with openings through which passes the rod 39. Said spring is mounted between the lugs 40 and 41 and owing to the bowed condition of its central portion, tends to draw its ends into annular recesses 44 and 45 formed in the rod 39 as indicated in Fig 3. The lower of these recesses is so placed as to be entered by the lower portion of the spring when the rod 39 is in its lower position and similarly the second recess 44 is placed to receive the upper end of the, spring when the rod 39 is at its highest position.

For operating the toothed member 50 we provide it with a perforated lug 46 and mount on the casing 1 a three-armed lever 47, pivoting this to said casing by means of a screw 48. One arm of this lever is designed to enter the perforation of the lug 46 while a second arm thereof projects horizontally outward so as to be conveniently actuated by the foot of the operator. A third arm 49 of the lever extends upwardly adjacent one edge of the casing cover 3 which is marked, preferably as -two extreme positions of this indicating arm.

Under operating conditions when it is desired that the operating lever 6 shall be free to return to its off or normal position from any displaced position as soon as the foot of the operator is withdrawn, the lever 47 is so shifted that its indicating arm 49 is opposite or adjacent the part of the easing edge marked Free. Under these conditions the toothed member 50 is raised above the plane of the two pawls or holding arms 20 and 21 and as a consequence when the operating lever 6, after having been moved from its normal or off position, is no longer held displaced, it at once returns to said normal position under the action the lug 23. Such a condition of operation is highly advantageous when the electric motor whose action is governed by the controller is used for delicate drilling, when it may be desirable to stop the motor at frequent intervals or stop the operation of the tool in a minimum time in case of an accident or for any other reason. On the other hand, when it is desired to use the motor governed by the controller for an operation in which the same speed is desired for more or less prolonged eriods of time, the lever 47 is so turned on its pivot screw 48, as to bring its indicating arm opposite the word Lock, thereby causing the rods 38 and 39 to be moved downwardly and with them the toothed member 50, so that this latter is in the plane of the pawls or holding elements 20 and 21. As a consequence the controller is then capable of operation in the manner described in a patent granted to Adolph W. Schramm, No. 691,187, dated January 14, 1902. Thus when the operating lever 6 is deflected toward the right, the pawl or holding element 21 engages one of the teeth 36 of the member 50, thereby retaining said lever in a corresponding posi tion and causing operation of the motor at a definite speed. When, however, the lever is tripped by the foot of the operator, this pawl disengages the tooth which has hitherto held it and under the action of the spring 12 is returned to its normal or off position. The peculiar construct-ion of the operating lever and its associated parts whereby this peculiar action occurs is clearly described and claimed in the patent aforesaid.

From the above description it will be seen that by the manipulation of the lever 47, the operating lever 6 may be operated altogether independently of the toothed member 50, or on the other hand, may be retained in any of several positions when said strip is lowered.

It is, of course, obvious that instead of moving the toothed strip or member 50 into and out of operative position, we may provide what may be termed a masking piece as shown in Figs. 7 and 8 to attain a similar object. In such acase a toothed strip 50 similar in construction to the strip 50 would be rigidly fastened to or mounted on the frame 7 in such position as to be engaged by the pawls 20 and 21 under operating conditions. Adjacent this strip is mounted a substantially semi-annular member 51, connected to and guided by rods 38 and 39, and provided with an operating lever arranged as shown in Fig. 8. The dimensions and proportioning of this masking strip 51 are such that in one position it presents its curved inner edge to the pawls 20 and 21, so as to hold these out of engagement with the teeth of the strip 50. When, however, said piece 51 has been moved, as by operation of the lever 47 away from the toothed piece 50, the pawls are thereafter free to engage the teeth 36 and 37 so as to hold the foot operating lever 6 in running position. While this alternate construction may be used without departing from our invention, we preferably employ that shown in Figs 1 to 6 of the drawings.

Another possible variation of the invention may be constructed as in Figs. 9 to 11 in which we provide means acting on the pawls to keep them from engaging the teeth of the toothed or holding memberwhen this is desirable. For this purpose there is pivoted to the pawl structure two levers 52 and 53 mounted to be respectively adjacent the pawls 21" and 20. In this case the toothed member 50 is fixed and has on it two cams 54 and 55 so placed as to be capable of respectively engaging the levers 52 and 53 under certain conditions; Said levers have their cam-engaging ends drawn together by a spring 56 and the other end of the lever 53 has a pin 57 so placed as to engage the adjacent end of the lever 52. On the main operating lever 6 is a locking lever 58 designed to force the levers 53 and 52 through the pin 57 toward the central spindle 8. With this construction the levers 52 and 53 normally have their cam-engaging ends so drawn together by the spring 56 that they cannot engage the cams 54 and 55; hence when the main lever 6 is moved from its central position, it is held in its displaced position by the pawls 20 and 21 and the member 50, as hereintofore described' If, however, the locking lever 58 be moved to the position shown in full lines in the figures, the two levers 5253 have their cam-engaging ends locked in such positions that when the main lever 6 is moved from its ofl position, they will engage their respective cams and by moving the parts 6 and 18 relatively to each other, prevent the pawls from enga ing the toothed member 50". The operating lever thus necessarily returns to its off position from any point at which it may be released by the operator. I I,

It will be noted from Figs. 2 and 7 that the side elements of the removable frame 7 are designed to cooperate with suitably formed recesses or guideways in the casing 1 so as to be easily inserted in or removed from the same ;the lever or trigger 47 turning on its pivot 48 to permit of this action, as it moves into or out of engagement with the lug 46 of the member 50.

We claim 1. An electric controller having an operating lever made in two relatively movable parts; a toothed member placed to cooperate with an arm on one of said parts of the lever to retain it in any of a number of definite positions; with means for bodily moving said member into and out of the plane of movement of said lever arm.

2. An electric controller having a frame; an operating lever; a toothed member slidably guided on the frame and placed to cooperate with an arm of said lever to retain it in any of a'number of definite positions; with means for bodily moving said member into and out of operative position.

3. An electric controller having an operating. lever made in two sections pivoted together; a toothed bar; and an arm on one of said lever sections capable of engaging said toothed bar to retain the lever in any of a number of given positions; said toothed bar being movable out of and into a position in which it may be engaged by the lever arm.

4. The combination in a controller of a supporting frame; a spindle supported by the frame; an operating lever made in two relatively movable parts of which one is mounted co-axially with the spindle and the other is provided with an arm; and a holding member mounted on the frame so as to be movable at will out of and into a position to be engaged by said lever arm.

5. A controller including a lever having 5 tion without engaging any of said teeth after one of its arms has been disengaged from one of them; and means for moving said toothed bar out of and into position'to be engaged by said lever arms. 4

6. The combination in a controller of a supporting frame; a lever mounted thereon and including two parts pivoted together; one of said parts having a plurality of holding arms; a segmental toothed bar for engaging said arms to hold the lever in a displaced position; and means for moving said bar out of and into position to be engaged by said arms.

7. The combination in a controller of a supporting frame; a lever mounted thereon and including two parts pivoted together; one of said parts having a plurality of holding arms; a segmental toothed bar for engaging said arms to hold the lever in a displaced position; and means for rendering the toothed bar inoperative at will to hold said lever arms.

8. The combination in a controller of a supporting frame; a lever mounted thereon and including a holding arm; a toothed member for engaging said arm to hold the lever in a displaced position; and means for rendering the toothed bar inoperative at will to hold the lever arm.

9. The combination in a controller of a supporting structure; a frame removable from said structure; motor controlling mechanism mounted on said frame and in eluding an operating lever; a member mounted on the frame for holding said operating lever in any of a number of positions; and means for moving said member into and out of operative position.

10. A controller consisting of a casing; a framework removably mounted therein; motor controlling mechanism on said framework including an operating member having a holding arm or arms; atoothed bar movably mounted on said frame; and means on the casing removably engaging said bar for moving it out of and into position to engage the holding arm of the operating member.

11. The combination in a controller of a supporting structure; motor controlling mechanism including an operating lever; a holding member for said lever movable into and out of operative position; and an actuating lever for said member mounted on the casing.

12. The combination in a controller of a supporting structure; motor controlling and, out of operative position; and a lever including an indicating arm for actuating said member.

13. The combination in a controller of a supporting structure; motor controlling mechanism including an operating lever; a holding member for said lever movable into and out of operative position; with an actuating lever. for said member mounted on the casing and including an arm loosely and re- -movably engaging the holding member.

14. The combination in a controller of a framework; motor controlling means mounted thereon and including an operating lever having a holding arm or arms; a toothed bar; guiding members on the frame for said bar; and means for moving the bar out of and into position to be engaged by the holding arm of the lever.

15. The combination in a controller of a framework; motor controlling means mounted thereon and including an operating lever having a holding arm or arms; a toothed bar; guiding members on the frame for said bar; means for moving the bar out of and into position to be engaged by the holding arm of the lever; and means tending to retain the bar in either of two positions.

16. The combination in a controller of a supporting frame; an operating lever having a holding arm; a toothed bar for said arm; guide rods movably mounted on the frame and connected to said toothed bar; means for moving the bar into and out of the path of movement of the holding arm;"and a spring tending to retain said toothed bar in any of a number of definite positions.

17. The combination with a controller having an operating lever, of means for holding said lever in a given position; the same consisting of a movable member; a guide bar for said member having an annular recess; with a spring placed to engage said recess to hold said bar in a definite position.

18. The combination with a controller having an operating lever, of means for holding said lever in a given position, the same c011- sisting of a movable member; means for holding said member in a definite position consisting of a longitudinally movable bar provided with a recess; a structure supporting said bar; and a spring having a perforated portion for the reception of said bar, said spring being formed to draw the edge of its perforated portion into the recess.

19. The combination in a controller of a frame; an operating lever; means for holdoperating member therefor; means for holding said operating member in any desired position, said means including a member movable into and out of operative position; a supporting f ame; means for guiding said member on the f ame consisting of a longitudinally movable bar operative in hearings in the frame, said bar having two recesses; and a spring provided with two perforated portions for the reception of the bar; said spring being formed to tend to cause the edges of its perforated portions to enter the recesses of the bar. I

21. The combination in a controller of a casing; a frame removably mounted therein; motor controlling mechanism including an operatinglever carried by said frame; means including a movable member for releasably retaining said lever in any of a number of operating positions; with a governing device for said member mounted on the casing and detachably engaging the same.

22. The combination in a controller of a casing; motor controlling mechanism including an operating vmember removably mounted therein; locking means for retaining said member in any of a number of desired positions; and a member movably mounted on the casing and detachably engaging a portion of said locking mechanism so as to permit of the motor controlling mechanism being removed from or inserted in the casing.

28. The combination in a controller of a casing; motor' controlling mechanism including an operating member mounted in the casing and bodily removable therefrom; means forretaining said operating member in any of a number of positions, with means on the casing for governing said retaining means.

24. The combination in a controller of a casing; motor controlling mechanism including an operating member mounted in the casing; a locking device for retaining said operating member in any of a number of positions; and means on the casing for actuating said device.

25. The combination in a controller of a casing; motor controlling mechanism mounted therein and bodily removable therefrom, said mechanism including an operating member; and means for holding said members in any of a number of positions; with a trigger on the casing for rendering said holdingmeans operative or inoperative at will.

In testimony whereof, we have signed our names to this specification, in the presence of two subscribing witnesses.

ADOLPH \V. SCHRAMM. EDWARD B. WILFORD.

Witnesses:

WILLIAM E. BRADLEY, WM. A. BARR. 

